Skin Pathology
description
Transcript of Skin Pathology
Flat lesion• Macule : Flat, circumscribed area distinguished from
surrounding skin by coloration
Clinical terms
Excoriation
• A traumatic lesion characterized by breakage of the epidermis, causing a linear area usually due to scratching.
Clinical terms
Lichenification
• Thickened skin characterized by prominent skin markings
• usually the result of repeated rubbing
Clinical terms
Epidermis :Stratum corneum( keratin layer )Stratum granulosum ( granuler layer )Stratum spinosum( spinous layer )Stratum basalis ( basal layer)
Dermis
pathologic terms
KERATINOCYTES
Thickening of stratum corneum
Hyperkeratosis Parakeratosis
normal
retention of the nuclei
pathologic terms
Dyskeratosis
• Abnormal keratinization occurring prematurely within individual cells below the stratum granulosum
pathologic terms
Skin Pathology
Clinical and pathologic termsInflammatory Skin Disorder1. Eczema2. Lichen planus3. PsoriasisSkin Tumors
Eczema
• The word ‘eczema’ comes from the Greek ‘boiling’ a reference to the tiny vesicles that are often seen in the early acute stages of the disorder, but less often in its later stage
غليان
Eczemaclinical features
• Acute : pruritic (itchy), edematous, plaques, often containing small and large blisters (vesicles and bullae)
• Chronic: persistent antigen stimulation, lesions may become less "wet" and progressively scaly as the epidermis thickens.
Causes of eczema
Poison Ivyacids, bases
drug , food
Clinical conditions
1. Atopic dermatitis 2. Allergic contact dermatitis3. irritant contact dermatitis 4. Drug-related5. Photoallergic dermatitis
Atopic dermatitis
• Pathogenesis:• Immune dysfunction resulting in IgE
sensitization • The skin of a patient with atopic dermatitis
reacts abnormally and easily to irritants, food, and environmental allergens
Atopic eczema
• Cheeks and flexural surfaces of the joints are the most commonly affected regions.
• Family history of eczema and bronchial asthma
Allergic Contact Dermatitis Pathogenesis
initial exposure to an environmental contact sensitizing agent
processed by epidermal Langerhans cells
migrate to draining lymph nodes and present the antigen to T cells
Memory T cell
on re-exposure to the antigen, CD4+ T lymphocytes migrate to the affected skin
they release cytokines that recruit additional inflammatory cells
LN T cell
DELAYED TYPE HYPERSENSITIVITY
Psoriasis• A common chronic inflammatory dermatosis
affecting 2% of people in the United States. • Sometimes, it is associated with arthritis,
myopathy, enteropathy, and heart disease.
Pathogenesis of Psoriasis
immunologic + genetic susceptibility + environmental factors
• Sensitized T cells secrete cytokines and growth factors that induce keratinocyte hyper-proliferation
Clinical Features of Psoriasis• Site: skin of the elbows, knees, scalp, lumbosacral areas, intergluteal
cleft, and glans penis
• Appearance: a well-demarcated pink plaque covered by loosely adherent silver-white scale
epidermal thickening (acanthosis )parakeratosisthinning of suprapapillary plates) The blood vessels within the papillae are dilated and tortuous. These vessels bleed readily when the scale is removed, giving rise to multiple punctate bleeding points (Auspitz sign). Neutrophils 1. epidermis (pustules of Kogoj) 2. stratum corneum (Munro microabscesses).
acanthosis
parakeratosis
thinning of suprapapillary plates)
CHRONIC INFLAMMATORY DERMATOSES
• Persistent inflammatory dermatoses that exhibit their most characteristic features over many months to years
–Psoriasis –Lichen Planus
Lichen Planus clinical
Pruritic, purple, polygonal, papuleswhite lines, called Wickham's striaedisorder of skin and mucous membrane. In 70% of cases, oral lesions are present
Interface dermatitis, basal keratinocytes that show degenerationsawtoothing.
Morphology
Interface dermatitis, is characterized by a dense, continuous infiltrate of lymphocytes along the dermoepidermal junction basal keratinocytes show degeneration and apoptosisThis pattern of inflammation causes the dermoepidermal interface to assume an angulated contour ("sawtoothing").
Premalignant Epithelial Lesions
• Skin dysplasia results of chronic exposure to sunlight and is associated with hyperkeratosis
Actinic Keratosis
Clinical Features• Site: sun-exposed areas (face, arms, dorsum of the hands).• The lesions can be treated with local cryotherapy (superficial freezing) or topical chemotherapeutic and other agents.
Actinic Keratosis
Morphology• Lower portions of the epidermis show cytologic atypia, • The dermis contains thickened, blue-gray elastic fibers (solar
elastosis), the result of chronic sun damage & lymphocytes • The stratum corneum …….parakeratosis
Squamous Cell Carcinoma(SCC)
• sun-exposed sites in older people• lightly pigmented people.• Other predisposing factors include:
1. industrial carcinogens (tars and oils),2. chronic ulcers3. old burn scars4. ionizing radiation.
Pathogenesis of SCC• The most common exogenous cause of cutaneous squamous
cell carcinoma is UV light exposure,
1. immunosuppressed patients as a result of chemotherapy or organ transplantation,
2. xeroderma pigmentosum [inherited defects in DNA repair].
Increase riskp53 mutations
Morphology of SCC• Squamous cell carcinoma in situ is characterized by atypical
cells at all levels of the epidermis, with nuclear crowding and disorganization.
Prognosis of SCC
• Invasive squamous cell carcinomas of the skin are often discovered while small and resectable; less than 5% have metastases to regional nodes at diagnosis.
• Mucosal squamous cell carcinomas (oral, pulmonary, esophageal, etc.) are generally a much more aggressive
Basal cell carcinoma• The most common human cancer, • slow-growing tumor that rarely metastasizes. • chronic sun exposure and in lightly pigmented people.
• Increase risk [same as squamous cell carcinoma]1. immunosuppressed patients as a result of chemotherapy or organ
transplantation, • xeroderma pigmentosum [inherited defects in DNA repair].
Pathogenesis of BCC
• dysregulation of PTCH pathway. PTCH functions as a classic tumor suppressor.
• mutations in p53 are also common.
Nevoid Basal Cell Carcinoma Syndrome [GORLIN SYNDROM]
Clinical Features of BCC
• Papule or nodule, often containing prominent, dilated subepidermal blood vessels (telangiectasia)
Morphology of BCC• Tumor cells resemble the normal epidermal basal cell layer .• Peripheral tumor cell nuclei align in the outermost layer
(palisading) with separation from the stroma
Dysplastic nevi1. Sporadic form Not
precursors of melanoma
2. familial form autosomal dominant fashion and is considered precursors of melanoma
Clinical Feature of Dysplastic Nevi
• usually larger than most acquired nevi (often >5 mm across) and may occur as hundreds of lesions on the body surface in familial cases
• They usually show variable pigmentation (variegation) and irregular borders
Melanomamalignant tumor of melanocytes
• Melanoma is less common but much more deadly than basal or squamous cell carcinoma.
Melanoma
• sunlight plays an important role in the development of melanoma
• More common in fair skinned persons
Clinical feature of Melanoma
• Site: – most of these lesions arise in the skin– other less common sites of origin include :• oral and anogenital mucosal surfaces• esophagus• meninges• eye
Clinical feature of Melanoma• The most important clinical sign of the disease is a
change in the color or size of a pigmented lesion.• Unlike benign nevi, melanomas exhibit striking
variations in pigmentation,• ABCD principle • asymmetry, border, color, diameter.
Melanoma
nevus
Pathogenesis of malignant transformation
• is a multistep process with activating mutations in proto-oncogenes and loss of tumor suppressor genes
• Germ-line mutations in the CDKN2A gene (located on 9p21) are found in 40% of individuals with familial melanoma
Morphology
Malignant cells grow as poorly formed nests or individual cells at all levels of the epidermis
vertical growth
radial growth
rarely metastasized
Commonly metastasized
Morphology of Melanoma• Individual melanoma cells are usually
considerably larger and more atypical than nevus cells.
• The probability of metastasis is predicted by:1. measuring the depth of invasion in millimeters
of vertical growth phase nodule below the top of the granular cell layer of the overlying epidermis (Breslow thickness).
2. overlying ulceration3. mitotic rate
Metastases
• In some cases, metastases may appear for the first time many years after complete surgical excision of the primary tumor, suggesting a long phase of dormancy
Prognosis• It is vitally important to recognize melanoma as early as
possible. • Depend on Breslow thickness ( > 1mm , bad prognosis)• The vast majority of superficial lesions are cured surgically
[radial growth phase]• melanomas that become metastatic have a virtually uniformly
poor prognosis, with no effective therapy in most cases.
1. Macule2. Papule3. Plaque4. Blister Vesicle, Bulla,
5. Pustule6. Scale
a) Discrete, pus-filled raised area b) Elevated solid area = < 5 mmc) Elevated flat-topped aread) Dry, horny, platelike excrescence; e) Flat, circumscribed area f) Fluid-filled raised area
1. Hyperkeratosis2. Parakeratosis3. Acanthosis4. Dyskeratosis5. Acantholysis6. Spongiosis
a) Epidermal hyperplasiab) Intercellular edema of the epidermis c) Abnormal keratinization occurring
prematurely within individual cellsd) Thickening of stratum corneume) Hyperkeratosis with retintion of nucleif) Loss of cohesion between keratinocytes
Clinical features
1. associated with arthritis2. Atopic dermatitis3. Auspitz sign4. Nail changes occur in 30% of cases5. Pruritic, purple, polygonal, papules6. elbows, knees7. Family history bronchial asthma
a) Eczema
b) Lichen planus
c) Psoriasis
Histological features
1. Sawtoothing2. Apoptosis in basal
keratinocytes3. Spongiotic dermatitis4. Neutrophil infiltration
of epidermis5. Interface dermatitis6. Dilated blood vessels
in papillary dermis
a) Eczemab) Lichen planusc) Psoriasis
1. Premalignant Epithelial Lesions
2. Breslow thickness3. slow-growing tumor that
very rarely metastasizes4. Lentigo maligna 5. sun-exposed areas6. dysregulation of PTCH
pathway7. lightly pigmented people8. variations in pigmentation
a) Actinic Keratosis
b) Squamous Cell Carcinoma
c) basal cell carcinoma
d) Melanoma
e) Melanocytic Nevi
Describe the lesionWhat is your diagnosis
1. Macule2. Papule3. Plaque4. Blister Vesicle, Bulla, 5. Pustule6. Scale